汽車專業(yè)英語(yǔ)課件：Electrical and electronic system -

汽車專業(yè)英語(yǔ)Electricalandelectronicsystem

5.1StructuralDrawingandTerminology1.VSV(forEVAP)(真空轉(zhuǎn)換閥<用于碳罐>)2.enginecoolanttemp.sensor(發(fā)動(dòng)機(jī)冷卻溫度傳感器)3.VSV(forEGR)(真空轉(zhuǎn)換閥<用于廢氣再循環(huán)>)4.EGRvalve(廢氣再循環(huán)閥)5.throttlepositionsensor(節(jié)氣門(mén)位置傳感器)6.knocksensor(爆震傳感器)7.airfuelratiosensor(空燃比傳感器)8.airfuelratiosensor(空燃比傳感器)9.heatedoxygensensor(加熱型氧傳感器)10.heatedoxygensensor(加熱型氧傳感器)11.crankshaftpositionsensor(曲軸位置傳感器)12.camshaftpositionsensor(凸輪軸位置傳感器)13.knocksensor(爆震傳感器)14.ignitioncoilwithigniter(帶點(diǎn)火器的點(diǎn)火線圈)15.VSV(forACIS)(真空轉(zhuǎn)換閥<用于聲頻控制進(jìn)氣系統(tǒng)>)Fig.5-1EFIsystem5.2InstrumentPanelVehicleinformationdisplayingsystem(asshowninFig.5-2)isoneoftheimportantsystemsoftheautomobile.Thedrivercanknowwhetherthecars,especiallythevariousoperatingparametersoftheenginearenormalorordertotaketimelymeasurestopreventtheoccurrenceofphysicalandmechanicalaccidents.Traditionalinstrumentswidelyusethecombinationanalogdisplayinginstruments,andvariousmeasuringinstrumentsarefixedonthedashboardinfrontofthedriver’sseat.Theinstrumentationsareindifferentvehicleinstrumentpanel.Theinstrumentscommonlyusedincludespeedometer,enginetachometer,oilpressuregauge,watertemperaturegauge,fuelgauge,ammeter,etc.Changesofthemonitoredobject’sstatusaredirectlyshowninmostinstrumentsthroughthesensors.Withthedevelopmentofautomotiveelectronictechnology,multifunctional,high-precisioninstrumentwithintuitivereadings,whichisshownbyelectronicdigitalandimage,hasbeenusedinvehiclescontinuously.傳統(tǒng)的儀表廣泛使用組合式模擬顯示儀器，各種測(cè)量?jī)x器是固定在駕駛員的座位前面的儀表盤(pán)上的。這些儀表設(shè)備在不同的車輛儀表板上有所不同。analogdisplaying模擬顯示5.2.1Indicators1.LowOilPressureIndicatorItisanengineoilpressurewarninglight.ThelightshouldcomeoneverytimewhenignitionkeyisturnedtoONorSTART,andshouldgooffwhentheenginestarts.Ifthelightstaysonorcomesonwhiletheengineisrunning,youhavelostoilpressureandcontinuedoperationwillcausesevereenginedamage.Stopandcheck.2.ChargingSystemIndicatorThislightcomesoneverytimewhenyouturnyourignitionkeytoONorSTART.Thelightshouldgooffwhentheenginestartsandthealternatorbeginstocharge.Ifthelightstaysonorcomesonwhentheengineisrunning,havethechargingsystemcheckedassoonaspossible.低油壓指示器。這是一個(gè)發(fā)動(dòng)機(jī)機(jī)油壓力警示燈。每當(dāng)點(diǎn)火鑰匙轉(zhuǎn)到開(kāi)或開(kāi)始時(shí)，這個(gè)燈都會(huì)點(diǎn)亮，當(dāng)發(fā)動(dòng)機(jī)開(kāi)始運(yùn)轉(zhuǎn)時(shí)，這個(gè)燈就熄滅。如果在發(fā)動(dòng)機(jī)正在運(yùn)轉(zhuǎn)時(shí)，這個(gè)燈點(diǎn)亮的話，表明你已經(jīng)失去了油壓并且持續(xù)的操作將導(dǎo)致發(fā)動(dòng)機(jī)的嚴(yán)重?fù)p壞。停車并檢查。3.ParkingBrakeandBrakeSystemIndicatorThislighthastwofunctions:Itlightsasareminderthatyouhavesettheparkingbrake.Onsometypes,thelightgoesonbrieflywhentheignitionswitchisturnedtoSTARTwiththeparkingbrakereleased.Drivingwiththeparkingbrakesetcandamagethebrakesandtires,andcausetheABStoturnoff.Itcanindicatethebrakefluidlevelislowifitremainslightafteryoureleasetheparkingbrakeorcomesonwhiledriving.Thisisnormallyduetowornbrakepads.Haveyourdealercheckthebrakingsystemforwornpadsorfluidleaks.4.SeatBeltIndicatorandBuzzerThisindicatorlightswhenyouturntheignitionswitchtoON.Itisaremindertoyouandyourpassengerstoprotectyourselvesbyfasteningtheseatbelts.Abeeperalsosoundsofyouhavenotfastenedyourseatbeltanditwillstopafterafewseconds.Butthelightstaysonuntilyoudo.Boththelightandthebeeperstayoffifyoufastenyourseatbeltbeforeontheignition.5.CheckEngineIndicatorThislightcomesonwhentheengineelectroniccontrolsystemisnotworkingproperly.Takevehicletothedealerimmediately.6.Anti-lockBrakeSystem(ABS)IndicatorThislightnormallycomesonwhenyouturntheignitionswitchtoONandgoesoffaftertheenginestarts.Ifitcomesonatothertime,thereisaproblemintheABS.Ifthishappens,takethecartoyourdealertohaveitchecked,withthelighton,yourcarstillhasnormalbrakingbutnoanti-lock.7.DoorandBrakeLampMonitorTheappropriatelightcomesoninthisdisplayifthebootoranydoorisnotclosedtightly.Ifabrakelightdoesnotwork,thebrakelampindicatorcomesonwhenyoupushdownthebrakepedalwiththeignitionswitchON.Aburnedoutbrakelightisahazardwhendriversbehindyoucannotbetoldthatyouarebraking.Haveyourbrakelightrepairedrightaway.AllthelightinthemonitordisplaycomeonforafewsecondswhenyouturntheignitionswitchtoON.8.LowWasherFluidLightThislightilluminateswhenthereislessthanaquarterofthecontainerofwasherfluidleft.Addwasherfluid.9.LowFuelIndicatorThislightcomesonwhenyourfuelgaugeindicatesapproximately1/8fueloftank.Fillupthetankwithfuel.10.CruiseControlIndicatorThislightcomesonwhenyousetthecruisecontrol.Whenyoutapthebrakeorclutchpedal,orpresstheSETandRESUMEbuttonsatthesametime,thecruisecontrollightontheinstrumentpanelwillgooutandthecarwillbegintoslowdown.Youcanusetheacceleratorpedalinthenormalway.11.TractionControlSystem(TCS)IndicatorTheTCSlightnormallycomesonwhenyouturntheignitionswitchtoONandgoesoffaftertheenginestarts.Ifitdoesn’t,oritstaysonafterpossibleenginestarts.ThereisaproblemwiththeTCS.Checkitassoonaspossible.12.SupplementalRestrainSystem(SRS)IndicatorTheairbagwarninglightgoesontoalertthedriveroftroubleintheSRSsystemwhenamalfunctionisdetectedinthecenterairbagsensorassemblyself-diagnosis.InnormaloperatingconditionswhentheignitionswitchisturnedtotheONposition,thelightgoesonforabout6secondsandthengoesoff.13.BrakeFrictionPlateIndicatorThelightisusedtoshowtheconditionofthebrakefrictionplate.Itcomesonwhenthebrakefrictionplatehadproblemsorworntoomuch.Itturnsoffafterchangingthebrake.14.BrakepedalIndicatorThelightisusedonthenvehiclesthatareequippedwithautomatictransmission.ItpromptsyoucanshiftPgearorNgeartotheothergearswhenyousteponbrakingpedaldown.15.ElectronicStableProcedureControlSystemIndicator(ESPIndicator)Thelightisusedtoshowtheworkingconditionoftheelectronicstableprocedurecontrolsystemanditsproblems.ThelightcomesonforafewsecondswhenignitionkeyisturnedtoON,andthevehiclecarryonself-checking.Andthelightturnsoffafterafewseconds.Thelightstaysoniftheengineelectroniccontrolsystemhadproblems.Thelightstaysflashingifthesystemisworkingwhenyouaredriving.16.EnginecoolantTemperatureIndicatorThelightshouldcomesonforafewsecondswhenignitionkeyisturnedtoON,andthenitwillgooff.Ifthelightstaysonorflashing,itshowsthatthetemperatureofthefluidistoohighorthecoolantlevelistoolow.Soyoushouldturnofftheenginetocheckthecoolantlevel.FollowtheinstructionsintheMaintenanceBookandaddcoolantifnecessary.5.2.2Gauges1.TemperatureGaugeItshowsthetemperatureofthecoolantoftheengine.Duringnormaloperation,thepointershouldrisefromC(Cold)totheNORMALband.Whenyouaredrivinginheavytrafficoruphillinhotweather,thepointermayreachthetopoftheNORMALband.IfitreachestheH(Hot)band,theengineisoverheatingandmaycauseenginedamage.Stopandcheck.2.FuelGaugeItshowshowmuchfuelyouhaveinthefueltank.Forfuelgaugeproperoperation,theignitionswitchmustbeintheOFFpositionbeforeyouaddfueltothefueltank.Itisaccuratewhenthecarisonlevelground.Itmayvaryslightlywhilethevehicleisinmotion.溫度計(jì)顯示了發(fā)動(dòng)機(jī)冷卻劑的溫度。在正常操作期間，指針應(yīng)該從C(冷)上升到正常的范圍。當(dāng)你在車輛擁擠的路上駕駛或在炎熱的天氣下上坡時(shí)，這個(gè)指針可能達(dá)到正常的范圍的頂端。如果它到達(dá)H(熱)范圍，發(fā)動(dòng)機(jī)過(guò)熱并可能導(dǎo)致發(fā)動(dòng)機(jī)損害，停車并檢查。3.SpeedometerItshowsyourspeedinkilometersperhour(km/h).Onsometypes,whenthespeedisoverapproximately120km/h,abuzzersounds.4.TachometerItshowstheenginespeedinrevolutionperminute(r/min).Toprotecttheenginefromdamage,neverdrivewiththetachometerneedleintheredzone.5.OdometerThismetershowsthetotalnumberofkilometersyourcarhasbeendriven.Thetripodometershowsthenumberofkilometersormilesdrivensinceyoulastresetit.Toresetit,pressresetbuttontoreturnthetripodometertozero.5.3ElectronicDevicesManyelectronicdevicesareusedonmodernautomobiles.Thesedevicescanbebrokendownintotwogeneralgroups:thosethatpresentinformationandthosethatcontrolvehiclefunctions.5.3.1WarningandIndicationSystemElectroniccircuitsanddisplaydevicescanbeusedinplaceofconventionalgaugestopresentinformation.Wheninformationispresentedasdigits,ornumbers,itisknownasdigitalinformation.Informationalsocanbepresentedinspokenlanguage.Forexample,whenadoorisajarortheignitionkeyinthelock,amessageisplayedtoalertthedriver.警告和指示系統(tǒng)。電子電路和顯示設(shè)備可以用來(lái)代替常規(guī)儀表來(lái)顯示信息。當(dāng)信息作為數(shù)字被顯示時(shí)，它被稱為數(shù)字信息。信息也可以以聲音語(yǔ)言的形式提供。例如，當(dāng)一扇門(mén)是半開(kāi)或點(diǎn)火鑰匙插在車鎖內(nèi)時(shí)，這通知有助于提醒司機(jī)。5.3.2ComputersAcomputerisadevicethatprocesses,orchanges,rawdataintousefulinformation.Thedatathatcomputersreceiveandtheinformationtheydeliverareintheformofelectricalsignals.Processingtoconvertdatasignalsintoinformationsignalsisdirectedbyasetofinstructionsknownasaprogram.Computerscanbeusedtocontrolvehiclefunctions.Thedatamessagesfromsensorsareprocessedtoproduceanoutputdevicetocontrolvehiclefunctions.Themainpartsofabasiccomputercontrolsystemare:inputsensorscomputerprocessingunitoutputdeviceswiringconnectionsAnautomotivecomputercanbethoughtofasa“blackbox”.Ifagiveninputsignalispresentedtothecomputer,itshouldproduceacertainoutput.The“blackbox”simplyprocessestheinputandproducesanoutput.Afullunderstandingoftheinnerpartsandfunctionsofacomputerisnotnecessary.Youneedonlytobeabletodetermineiftheunitisworkingproperly.一個(gè)汽車計(jì)算機(jī)可以被認(rèn)為是一個(gè)“黑盒子”。如果給定的輸入信號(hào)提供給計(jì)算機(jī)，它應(yīng)該產(chǎn)生一個(gè)特定的輸出。“黑盒子”只是處理輸入并生成一個(gè)輸出。全面了解內(nèi)部部件和電腦的功能是沒(méi)有必要的，你只需要能夠確定這個(gè)單元是否工作正常。Virtuallyanymechanicalorelectricalfunctionofanautomobilecanbecontrolledbyacomputer.Intoday’scars,theuseofcomputersisbeingexpandedconstantly.Themostcommonusersforcomputercontrolsincurrentvehiclesinclude:electronicignitionfueldeliveryemissionscontrolscruisecontrolheatingandairconditioningautomaticgearboxsuspensionanti-lockbrakesystempowersteeringanti-theftsystem5.3.3FeedbackControlComputer,sensorsandoutputdevicescanbeconnectedtomonitorandadjustvehiclefunctionscontinuously.Forexample,anelectronically-controlledcarburetorcomputercanmaintaina14.7:1air/fuelratioaftertheenginereachesnormaloperatingtemperature.Aninputsignalfromanexhaustgasoxygensensorintheexhaustsystemisfedtothecomputer.Whentheoxygensensorinputsignalindicatesthattheair/fuelmixtureisvaryingfromtheidealmixture,thecomputerproducesanoutputsignalthatoperatesameteringneedlepositionedwithinacarburetorjet.Themeteringneedlecanbepositionedtoallowmoreorlessfueltoflowthroughthejet.Whentheidealair/fuelmixtureisattained,thecomputermaintainsasteadyoutputsignalthatholdstheneedlestationarywithinthejet.在排氣系統(tǒng)中的廢氣氧傳感器的一個(gè)輸入信號(hào)反饋到計(jì)算機(jī)中。當(dāng)氧傳感器輸入信號(hào)表明，空氣/燃料混合物變化到理想的混合比時(shí)，計(jì)算機(jī)產(chǎn)生一個(gè)輸出信號(hào)，會(huì)使儀表指針在噴油嘴中定位。5.3.4PassengerInertialRestraintSystemsAutomaticpassengerrestraintsystems(airbagandseat-belttighteningsystems)mustrespondassoonaspossibleintheeventofanaccidentinordertoprovidemaximumprotectionforthepassengers.Inthecaseoftheseat-belttighteningsystem,theseatbeltmustbetightenedaslongasthepassengershavenotnoticeablymovedforward.airbag(氣囊)2.powerstand-by(備用電源)3.controlunit(控制單元)4.seat-belttightener(安全帶緊線器)Fig.5-4PassengerrestraintsystemsInthecaseoftheair-bagsystem,itissufficientiftheairbagiscompletelyinflatedbythetimethepassengerhasmovedforwardapproximately20cmandcontactedtheairbag.Theairbagisinflatedwithinapproximately30msbyapyrotechnicgasgeneratorlocatedinthesteeringwheelhub.Theairbagpreventsthepassenger’sheadandupperbodyfromimpactingthesteeringwheel.Theseatbelttightenertakesupseat-beltslackinapproximately10ms,therebyallowingthepassengertodecelerateattherelativelyfavorablerateofthevehiclecabinthroughoutthecourseoftheaccident.Bothsystemsaretriggeredbyelectricalfiringpulsesfromthesensor.Thesensorsrequiredtotriggerautomaticrestraintsystemsmustreliablyrespondinaccidentsinwhichtheimpactspeedisroughly18km/horhigher.However,theymustnotrespondinnormaluse,evenonbumpyroads.Theymustalsonotrespondinminoraccidentsorduringworkshoprepairs.位于方向盤(pán)轂內(nèi)的煙火式氣體發(fā)生器使安全氣囊在大約30ms內(nèi)膨脹。安全氣囊防止乘客的頭部和上半身撞擊方向盤(pán)。安全帶的張緊裝置在大約10ms內(nèi)使安全帶松弛，從而允許乘客在整個(gè)事故的過(guò)程中以相對(duì)車輛艙室的有利的速率減速。兩個(gè)系統(tǒng)都是由傳感器的電點(diǎn)火脈沖進(jìn)行觸發(fā)的。5.3.5Anti-theftSystemEachyear,tensofthousandsofautomobilesarestolenorbrokeninto,inresponsetothisproblem,carmanufacturershaveofferedoptionalorstandard-equipmentanti-theftsystems.Severalcomponentsareneededtooperateananti-theftsystem.Thesepartsinclude:electroniccontrolunitfrontandreardoorswitchestrunkkeycylinderunlockswitchhoodswitchstarterinhibitorrelayhornrelaytheft-alarmhornAnti-theftsystemstypicallydisrupttheignitionand/orstartersystems,soundthehornatintervals,andflashheadlightstoalertthecarownerandattractattentiontothethief.Inaddition,thecarwillnotstart,eveniftheignitionkeyswitchisbrokenoutandturnedwithascrewdriver.Toarmmostsystems,thedriver’sdoorislockedwiththekeyorthediver’sdoorknobisdepressedandthehandleisliftedwhenthedoorisclosed.Asecuritylightonthedashtypicallyilluminatesfor30stosignalthatthesystemwillfunction.Whenthelightgoesout,thealarmandotherfunctionsarearmed.Ifadoor,hoodortrunkisforcedopen,thealarmistriggered.Thesystemwillcontinuetosoundandflashawarningfortwotothreeminutes.Then,ifthedoor,hoodortrunkhasbeenclosed,thesystemwillshutitselfoffandresetthealarmautomatically.Thetrunkcanbeopenedwiththekeytoloadpackagesorcargo.Thealarmwillnotbetriggered,andthealarmwillresetautomatically30safterthetrunklidisclosed.Todisarmthesystemcompletely,thediver’sdoormustbeopenedwiththekey.如果車門(mén)，發(fā)動(dòng)機(jī)罩或車尾的行李箱被強(qiáng)行打開(kāi)，警報(bào)器就會(huì)被觸發(fā)。該系統(tǒng)將以持續(xù)的發(fā)出聲響和閃爍報(bào)警兩到三分鐘。然后，如果車門(mén)，發(fā)動(dòng)機(jī)罩或車尾的行李箱已經(jīng)被關(guān)閉，該系統(tǒng)將自我關(guān)閉并且自動(dòng)重置報(bào)警。5.4CANandLIN5.4.1AutomotiveControllerAreaNetworkApplicationsThecontrollerareanetwork(CAN)isaserial,asynchronous,multi-mastercommunicationprotocolforconnectingelectroniccontrolmodulesinautomotiveandindustrialapplications.CANwasdesignedforautomotiveapplicationsneedinghighlevelsofdataintegrityanddataratesofupto1Mb/s.Thekeybenefitsinclude:TheautomotivenetworkingstandardprotocolforEurope.SupportstheUSautomakersmigrationtoCANforbodyelectronicsbuses.1.DifferentCANNetworksHaveDifferentPerformanceNeedsNotallCANnetworksarecreatedequal.Intheautomotiveenvironment,CANnetworkscanbesplitintotwodistinctcategoriesbasedonthenatureofthetrafficonthenetwork.Bodycontrolnetworks,dealingwithpassengercomfortandconveniencesystems.forexample,dealwithawiderangeofmessageidentifiersthatappearinnoparticularorderorfrequency.Incontrast,powertrainnetworksthatpassinformationrelatingtoengineandtransmissioncontrolhaveamuchlowernumberofdifferentmessagestodealwith,butthemessagesappearveryregularly.Thesedifferencesinmessagingresultinverydifferentapproachestodesigninghardwareandsoftwaresystemstodealwiththedemandseachtypeofnetworkplacesoneachnodeinthatnetwork.并非所以的控制器局域網(wǎng)是完全相同的。在汽車環(huán)境下，可以將CAN網(wǎng)絡(luò)可以按照在互聯(lián)網(wǎng)上交通流的自然屬性將交通網(wǎng)絡(luò)分成兩個(gè)不同的類別。車體控制網(wǎng)絡(luò)，乘客的舒適和方便的系統(tǒng)，例如，處理不以特定的順序或頻率出現(xiàn)的廣泛的消息標(biāo)識(shí)符。相比之下，在與發(fā)動(dòng)機(jī)和變速箱控制相關(guān)的傳遞信息的傳動(dòng)系統(tǒng)網(wǎng)絡(luò)，有一個(gè)相對(duì)較少的不同信息要被處理，但是這個(gè)信息顯得很有規(guī)律。2.DifferentCANNetworksHavePhysicalLayerRequirementsCAN,likeallmajornetworkingprotocols,requiresaphysicallayerdevicetocommunicate.ThisphysicallayercomesfromtheISO/OSIsevenlayerstackmodelandisresponsibleforcurrentandvoltagecontrolforthebus.Itdealswithcurrentandvoltagetransientsandsignalingbus(line)faultsandworkstopossiblycorrectthem.TheBoschCANspecificationdoesnotdictatephysicallayerspecificationsforanyoneimplantingaCANnetwork.Thisisbothablessingandacuretothedesigner.Overthecourseofthelastdecide,twomajorphysicallayerdesignshavecometotheforefrontandbecomethebasicphysicallayerdesignsusedinmostCANapplications.Theybothcommunicateusingadifferentialvoltageonapairofwiresandarecommonlyreferredtoasahigh-speedandalow-speedphysicallayer.Thelow-speedarchitecturehastheabilitytochangetoasingle-wireoperatingarchitecture(referencedoffground)whenoneofthetwowiresisfaultedthroughashortoropen.Becauseofthenatureofthecircuitryrequiredtoperformthisfunction,thisarchitectureisveryexpensivetoimplementatbusspeedsabove125Kb/s.Thisiswhy125Kb/sisthedividinglinebetweenwhatisconsideredhigh-speedandlow-speedCAN.Althoughbotharchitecturesuseavoltagedifferenceonapairofwires,theterminationmethodsforeacharedifferentandincompatibleinproductionsystems.OneadditionalCANphysicallayerhasrecentlybeendevelopedbyGeneralMotors.Thisphysicallayerusesonlyonewriteatalltimesthatlimitsitsspeedperformanceto33.33Kb/s.ThissinglewireCANphysicallayerisverydifferentfromtheothertwotypesandisnotyetwidelyaccepted.BecausetherearenorequirementsonthephysicallayerintheCANspecification,otherstandardsorganizationshavedevelopedstandardstohelpdesignerscreatecompatibleCANdevices.TheinternationalStandardsOrganization(ISO)andSocietyofAutomotiveEngineers(SAE)createthestandardsforEuropeandtheUnitedStatesrespectivelytoensureinteroperabilityofcomponentsatthephysicallayerandrecommendeddesignpractices.另一個(gè)CAN物理層最近被通用汽車所開(kāi)發(fā)。這物理層在任何時(shí)候僅使用一個(gè)寫(xiě)功能，限制其速度性能為33.33kb/s。這個(gè)單線的CAN物理層與其他兩種類型的物理層非常不同，尚未被廣泛接受。因?yàn)閷?duì)于CAN的物理層規(guī)范中沒(méi)有要求，其他標(biāo)準(zhǔn)組織已經(jīng)開(kāi)發(fā)標(biāo)準(zhǔn)來(lái)幫助設(shè)計(jì)者創(chuàng)建兼容的CAN設(shè)備。5.4.2AutomotiveLocalInterconnectNetworkApplicationsLocalinterconnectnetwork(LIN)isaUART-based,single-master,multiple-savenetworkingarchitectureoriginallydevelopedforautomotivesensorandactuatornetworkingapplications.LINprovidesalow-costnetworkingoptionforconnectstheLINnetworkwithhigher-levelnetwork,likecontrollerareanetwork(CAN),extendingthebenefitsofnetworkingallthewaytotheindividualsensorsandactuators.Thekeybenefitsinclude:LINphysicallayerhascriticalwaveshapingthataidsEMCproblemsbyreducingradiatedemissions.Mechatronicssmartconnectorsolutionsofferincreasedintegrationofconnectorsandsiliconforgreaterdesignflexibilityandaddedfeaturecontent.1.FormFactor,ManufactureCapability,LoadControlandDiagnosticsChallengesExistWhenIntegratingLINNetworkingintoAnAutomotiveEnvironment.Mostapplications,whereLINcouldbeused,arecurrentlyimplementedusingdiscrete,point-to-pointwiringsystems,withnoallocationforsilicon,circuitsorcomponentsattheload.Theload,whetheralamp,motororsensor,isusuallyconnectedwithasimpleconnectortowiresinthetangleofthewiringharness.Asaresult,littleroomremainstoincorporatethecomponentstoenableLIN.Forexample,inapowermirror,asuppliermightplaceasmanyasthreemotors,heaterelement,electorchromicglassandmultiplelamps.Therecomponentsdonotleavemuchroomforotherpotentialrequirements.Thecapabilitytomanufacturecontrolmodulesisanothersignificantchallengetoautomotiveelectronicsmanufacturers.ThisproblemisnotuniquetoLINdevelopersbutitisaproblemnotalwaysfacedbymanufacturersofmotors,sensorsandactuators.Finally,whendistributingtheintelligenceofthesystemusingLIN,newoptionsbecomeavailabletodesigners.Motor,lampandsolenoidloadscannowbecontrolledattheorigin.DiagnosticdatacanbeeasilyrejectedthroughtheLINnetworkprovidinganunprecedentedlevelofcontrolandsystemlevelinformation.Thechallengeishowtoprovidethesiliconcontenttocontrolanddiagnosetheseloadsinasmallformfactorthatcanfitinaverysmallspace.對(duì)于汽車電子產(chǎn)品制造商而言，生產(chǎn)控制模塊的功能是另一個(gè)重大挑戰(zhàn)。這個(gè)問(wèn)題對(duì)于LIN開(kāi)發(fā)者并不唯一，它是一個(gè)對(duì)于發(fā)動(dòng)機(jī)、傳感器和制動(dòng)器制造商而言，要不時(shí)面對(duì)的問(wèn)題。最后，當(dāng)使用LIN來(lái)分配系統(tǒng)智能時(shí)，新選項(xiàng)對(duì)于設(shè)計(jì)師具有可用性。電機(jī)、燈和電磁線圈負(fù)載現(xiàn)在可以在最初狀態(tài)得以控制。診斷數(shù)據(jù)可以很容易地通過(guò)LIN網(wǎng)絡(luò)拒絕，提供了前所未有的控制水平和系統(tǒng)水平信息。挑戰(zhàn)在于如何提供硅含量控制和在小的形成因素下診斷這些載荷，并且可以適合裝載在一個(gè)很小的空間內(nèi)。2.StringentEMCRadiatedEmissionsRequirementsElectromagneticCompatibility(EMC)dealswithhowmultipleelectronicdevicesinteractbasedontheelectromagneticemissions,theyradiate(radiatedemissions)andhowtheyrespondtoradiatedemissionsfromoutsidesources(susceptibility).Thisisofenormousconcernintheautomotiveenvironmentduetothecloseproximityofaverywiderangeofelectronicsystemsanddevices.ItisveryimportantthattheLINnetworknotradiateverymuchenergy,sincethesepassinformationthroughlongwiresthatresultswitchingfromgroundtobattery-levelvoltages.Thislargevoltageswingcanbeapotentialsourceoflargeamountsofradiatedemissions,particularlyiflittlecareorattentionispaidtophysicallayerdevicedesign.5.5AntilockBrakeSystem(ABS)Anantilockbrakesystem(ABS)isaclosed-loopcontroldevicewithinthebrakingsystemwhichpreventswheellock-upduringbrakingand,asaresult,retainsthevehicle’ssteerabilityandstability.ThepurposeofABSistoallowthedrivertomaintainsteeringcontrolunderheavybrakingand,inmostcases,onmostsituationssuchaswetroadsurface,toshortenbrakingdistancesbyallowingthedrivertohitthebrakefullywithoutthefearofskiddingorlossofcontrol.ThemainABScomponentsare:wheel-speedsensors,hydraulicmodulator,andtheelectroniccontrolunit(ECU),etc.(SeeFig.5-5).1.wheelspeedsensor(車輪轉(zhuǎn)速傳感器)2.pumpandmotor(泵和馬達(dá))3.wheelspeedsensor(車輪轉(zhuǎn)速傳感器)4.wheelspeedsensor(車輪轉(zhuǎn)速傳感器)5.anti-lockbrakecontrolmodule(防抱死控制模塊)6.hydraulicassembly(液壓系統(tǒng))7.relays(繼電器)Fig.5-5Four-wheelantilockbrakesystemThewheel-speedsensorssensethespeedofrotatingofthewheels,andthisspeedinformationissenttotheelectronicunit(ECU).Theyworkinconjunctionwithatoothedwheeloratoothedring.Anelectromagneticsensorcomprisesacoilwindingwithapermanentmagnetcoreandpolein,thelatterbeingaccuratelyalignedinaradialoranaxialpositionwithatoothedwheel,butseparatedfromitsteethbyasmallalthoughcriticalairgap.Theteethofthetoothwheelorthesensorringactasasinglegenerator,sothatwheneachpassingtoothfacesthepolepinofthesensor,thechangingmagneticfieldinducesavoltageacrossthewinding.Abovewalkingpace,thisproducesafrequencyofsignalthatvariesinproportiontoroadwheelspeedandthussuppliestherequiredinputtothecontrolsystem.Someantilocksystemusesonlythreewheelsensors.Onesensorisusedateachfrontwheel,andonesensorislocatednearthedriveshafttosenselockupatbothrearwheels.Somelighttruckshaveantilockbrakesystemthatpreventlockupattherearwheelsonly,whicharecalledrearantilockbrakesystem(RABS).Asinglespeedsensorinthedifferential-gearassemblysensesrear-wheellockup.Thehydraulicmodulatorassemblyregulatesthepressuretothewheelbrakeswhenitreceivescommandsfromthecontrolunit.Themodulatorassemblycanmaintainorreducepressureoverthelevelitreceivesfromthemastercylinder.Themodulatorassemblyconsistsofthreehigh-speedelectricsolenoidvalves,twofluidreservoirsandaturndeliverypumpequippedwithinletandoutletcheckvalves.Themodulatorelectricalconnectorandcontrollingrelaysareconcealedunderaplasticcoveroftheassembly.當(dāng)接收到控制單元命令時(shí)，液壓調(diào)制器總成調(diào)節(jié)制動(dòng)輪的壓力。調(diào)制器總成可以保持和減少?gòu)闹鞲捉邮盏膲毫λ?。調(diào)制器總成包括三個(gè)高速電動(dòng)電磁閥，兩個(gè)液壓儲(chǔ)液罐和一個(gè)配備有進(jìn)口和出口止回閥的轉(zhuǎn)向輸送泵。調(diào)制器接線盒和控制繼電器被掩蓋在一個(gè)塑料蓋的總成下。TheECUmonitorstherateofchangeinthisfrequencytodetermineimpendingbrakelockup.Itcontainsallthesignalconditioningcircuitryandtheoutputcircuits.Theoutputcircuitscontrolthehydraulicunittoadjustthelinepressuretoeachcaliper.Theunitislocatedunderthedashpanelontheleftside,abovetheglovecompartmentandintheforwardpositionoftheelectronicboxinenginecompartment.Ifaproblemissensed,thecontrolunitwilllighttheinstrumentpanelwarninglamp.Thebasicoperatingprincipleofantilockbrakesystemisquitesimple.Antilocksystemsmodulatebrakeapplicationforceseveraltimespersecondstoholdthetiresatacontrolledamountofslip;allsystemaccomplishesthisinbasicallythesameway.Oneormorewheel-speedsensorsgeneratealternatingcurrentsignalswhosefrequencyincreaseswiththewheelrotationalspeed.AnECUcontinuouslymonitorsthesesignalsandifthefrequencyofasignaldropstoorapidlyindicatingthatawheelisabouttolock,thecontrolunitinstructsthatthewheelisagainrotatingnormally,thecontrolunitallowsincreasedhydraulicpressuretothebrake.Thisrelease-applycycleoccursseveraltimespersecondto“pump”thebrakeslikeadrivemightbutatamuchfasterrate.防抱死制動(dòng)系統(tǒng)的基本的工作原理相當(dāng)簡(jiǎn)單。防抱死系統(tǒng)每秒鐘調(diào)節(jié)輪胎在一定量下滑動(dòng)，所有系統(tǒng)在基本相同的方式下完成這些工作。一個(gè)或多個(gè)輪速傳感器產(chǎn)生交流電信號(hào)其頻率隨車輪轉(zhuǎn)動(dòng)速度的增加而增加。電子控制單元連續(xù)監(jiān)控這些信號(hào)，而且如果信號(hào)的頻率下降過(guò)快表明一個(gè)車輪即將鎖死，控制單元指示車輪再次轉(zhuǎn)動(dòng)正常，控制單元允許增加液壓制動(dòng)壓力。這個(gè)釋放請(qǐng)求周期每秒發(fā)生幾次，像一個(gè)驅(qū)動(dòng)器一樣“加壓”制動(dòng)器，但可能速度更快。Undernormalbraking,theABSisnotused,andthemastercylinderreactstobrake-pedalmovementtosendfluidpressureouttoeachwheelcylinder.Duringfull,ABS-controlledbraking,pressureisautomaticallyadjustedtopreventwheellockupwithconstantbrake-pedalforce.Thethreeprocessesinvolvedare:Maintainingbrakingpressure.Ifthewheelsarelikelytolockupthebraking,pressureatthewheelinvolvedisinitiallykeptconstantasopposedtobeingfurtherincreased.Reducingbrakingpressure.Ifthewheelstillcontinuestodecelerate,thepressureinthewheelbrakecylind